diff --git a/doc/Makefile.in b/doc/Makefile.in
index e050470..d334fdd 100644
--- a/doc/Makefile.in
+++ b/doc/Makefile.in
@@ -59,8 +59,12 @@
 NORMAL_UNINSTALL = :
 PRE_UNINSTALL = :
 POST_UNINSTALL = :
+build_alias = @build_alias@
+build_triplet = @build@
 host_alias = @host_alias@
 host_triplet = @host@
+target_alias = @target_alias@
+target_triplet = @target@
 
 EXEEXT = @EXEEXT@
 OBJEXT = @OBJEXT@